Semiconductor device technology uses electrical devices, e.g., transistors, resistors, capacitors, etc., to formulate vast arrays of functional circuits. In the manufacture of semiconductor device packages, one or more semiconductor dies are incorporated into a sealed package. Typical package styles include dual inline packages (DIP), zig-zag inline packages (ZIP), small outline J-bends (SOJ), thin small outline packages (TSOP), plastic leaded chip carriers (PLCC), small outline integrated circuits (SOIC), plastic quad flat packs (PQFP) and interdigitated leadframes (IDF). Some semiconductor device packages include an interposer substrate, such as a circuit board, that is connected to the semiconductor dies prior to encapsulation.
Manufacturers are under constant pressure to reduce the size of semiconductor device packages and to increase the packaging density. One conventional way to increase packaging density is to increase the number of semiconductor dies in a semiconductor device package. For example, in memory device packages, such as flash memory, dynamic random access memory (DRAM), or static random access memory (SRAM), a package can include two or more dies that are stacked on top of one another and/or aligned with one another side-by-side. Such configurations provide a memory storage capacity that is based on the aggregated storage capacity of the individual dies. A 16 GB memory can include, for example, four dies each having 4 GB of memory capacity or two dies have 8 GB of memory capacity. As another example, a 64 GB memory can include 16 dies each having 4 GB of memory, eight dies each having 8 GB of memory, or four dies each having 16 GB of memory.
One drawback to this packaging technique, however, is that individual dies can be damaged or rendered inoperable during the assembly process of the package. Thermal and mechanical stresses can strain, crack, or delaminate portions of the individual dies. The molding process can damage or disconnect interior interconnects (e.g., wire bonds). Also, a die may simply underperform after it is packaged. In these instances, the semiconductor device package is rendered inoperable, even if other dies in the package remain operable.
As the number of dies in a package increases, the likelihood of the package having a damaged or inoperable die likewise increases. For example, if there is a 97% likelihood that a single die in the package will yield, the likelihood that two dies will yield is approximately 94% (i.e., 97%{circumflex over (0)}2). In packages that incorporate four or eight dies, for example, the likelihood is reduced to 88.5% and 78.4%, respectively.